Soil alterations by chronosequence of pastures in crop-livestock-forestry systems

Abstract

The intensive use of land has accelerated the loss of soil quality, a process that can be avoided by adopting conservationist production systems, such as the Crop-Livestock-Forest Integration system – ILPF. The objective of this work was to measure the physical and chemical attributes of an Argiluvic Plinthsol under pasture chronosequence in a crop-livestock-forest integration system in Pindaré-Mirim in the state of Maranhão, Brazil. For the purpose of evaluation, the experiment contemplated two reference environments: scrubland with secondary vegetation in regeneration for approximately 20 years and native babassu forest with soils collected before the beginning of the project; and five succession times: degraded pasture (Urochloa brizantha cv. Marandu), and ILPF conducted in 2016, 2017, 2018 and 2019, also compared to reference environments. Undisturbed samples were collected in mini trenches at depths of: 0 – 10, 10 – 20, 20 – 30 and 30 – 40 cm to determine physical attributes (density, macroporosity, microporosity and total porosity). For the chemical attributes of the soil (pH, organic matter, phosphorus, aluminum, potential acidity, sum of exchangeable bases and base saturation), deformed samples were collected at the same depths. The data obtained were analyzed with the aid of descriptive statistics, analysis of variance and Tukey test at 5% significance level, and analysis of principal components and clustering. The ILPF 2019 pasture showed higher macroporosity values. For depths of 0 – 10, 10 – 20 and 30 – 40 cm, the phosphorus and base saturation variables showed higher values ​​in the 2018 ILPF.